RE : RE : [lwip-users] Weird behavior of lwIP with C functions

[Frédéric BERNON]

>Isnt it a socket api function?

netbuf_copy_partial is more a netconn api,than a socket one (but in current code, socket layer is based on netconn layer). But it's just to show you how to process a pbuf (where data can be in several blocks). So, don't use it directly, but look how it's implemented to do the same thing.

 

>I am only taking the data of the first current pbuf received

Be carefull, the "first current pbuf received" can be a chain: by example, if your port use a 128bytes pool size, and you receive a full packet (saying, 1500 bytes), the pbuf you will receive will be a pbuf chain of 12 "blocks" (~1500/128). More, if you only want to read the first pbuf of the chain, don't use "tot_len" (the total pbuf chain size), but "len" (the pbuf node size).

 

> more longer than 10 chars so I guess it shouldn't cause the software to crash

But with any "string" function (like sprintf), you HAVE TO alloc one byte more for the zero-terminal...

 

>regarding sprintf, is memcpy better?

Of course!!!

 

 

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-----Message d'origine-----
De : address@hidden [mailto:address@hidden De la part de Louis Filasky
Envoyé : mardi 10 juillet 2007 21:16
À : address@hidden
Objet : RE : [lwip-users] Weird behavior of lwIP with C functions

Hi Frederic,

Thank you for your quick reply,

Well, I was wondering about the netbuf_copy_partial function you talked to me about. Isnt it a socket api function? I am using the raw api and well, I can see what you mean when you say that there is a chain of pbuf when data is received and I am only taking the data of the first current pbuf received. You re right saying it could be handled better, still the command line I am sending to Virtex II are no more longer than 10 chars so I guess it shouldn't cause the software to crash. Besides I debugged the code by removing some
parts and see how the server behaves. No problem appears to come before i check the commandType variable with a strncpy, then in this if, it starts behaving weirdly.

Anyway, regarding sprintf, is memcpy better?

Thanks again,

Antoine.

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